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// Copyright 2019 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package flipcall
import (
"bytes"
"fmt"
"sync"
)
func Example() {
const (
reqPrefix = "request "
respPrefix = "response "
count = 3
maxMessageLen = len(respPrefix) + 1 // 1 digit
)
pwa, err := NewPacketWindowAllocator()
if err != nil {
panic(err)
}
defer pwa.Destroy()
pwd, err := pwa.Allocate(PacketWindowLengthForDataCap(uint32(maxMessageLen)))
if err != nil {
panic(err)
}
var clientEP Endpoint
if err := clientEP.Init(pwd); err != nil {
panic(err)
}
defer clientEP.Destroy()
var serverEP Endpoint
if err := serverEP.Init(pwd); err != nil {
panic(err)
}
defer serverEP.Destroy()
var serverRun sync.WaitGroup
serverRun.Add(1)
go func() {
defer serverRun.Done()
i := 0
var buf bytes.Buffer
// wait for first request
n, err := serverEP.RecvFirst()
if err != nil {
return
}
for {
// read request
buf.Reset()
buf.Write(serverEP.Data()[:n])
fmt.Println(buf.String())
// write response
buf.Reset()
fmt.Fprintf(&buf, "%s%d", respPrefix, i)
copy(serverEP.Data(), buf.Bytes())
// send response and wait for next request
n, err = serverEP.SendRecv(uint32(buf.Len()))
if err != nil {
return
}
i++
}
}()
defer func() {
serverEP.Shutdown()
serverRun.Wait()
}()
// establish connection as client
if err := clientEP.Connect(); err != nil {
panic(err)
}
var buf bytes.Buffer
for i := 0; i < count; i++ {
// write request
buf.Reset()
fmt.Fprintf(&buf, "%s%d", reqPrefix, i)
copy(clientEP.Data(), buf.Bytes())
// send request and wait for response
n, err := clientEP.SendRecv(uint32(buf.Len()))
if err != nil {
panic(err)
}
// read response
buf.Reset()
buf.Write(clientEP.Data()[:n])
fmt.Println(buf.String())
}
// Output:
// request 0
// response 0
// request 1
// response 1
// request 2
// response 2
}
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